1. Field of the Invention
The present invention relates to a particle focusing apparatus and a method for focusing particles. More particularly, the present invention relates to a particle focusing apparatus capable of enhancing focusing and a method for focusing particles by using the particle focusing apparatus.
2. Description of the Related Art
Flow cytometers have been widely used for cell sorting and counting in the field of medical diagnosis. Typically, cells or particles are injected into the capillary and hydrodynamically focused into a cell or particle stream constrained by two planar sheath flows or a concentric sheath flow. Then, this stream is passed through a sensing region for cell or particle counting or sorting. One of the key techniques of the flow cytometer is to focus the cells or the particles in a narrow region, where the cells or the particles may be highly concentrated. Nowadays, as micro-fluidic technology and micro-electromechanical systems (MEMS) technology are being developed, research is being conducted on a flow cytometer that can be miniaturized into lab-on-a-chip system.
Generally, it is reported that the hydrodynamic focusing of particulate materials in microchannels is achieved two-dimensionally by using sheath flows. However, in a conventional flow cytometer, the focusing should be performed three-dimensionally for the best performance. Therefore, nowadays, research is being conducted on fabricating microchannels on a lab-on-a-chip device for three-dimensional hydrodynamic focusing based on the sheath flow technique using three-dimensional channel geometry. In this case, complicated microchannels are inevitable, resulting in high manufacturing costs and low productivity. The objective of the present invention is to provide axisymmetric or three-dimensional focusing of the particles in a single straight channel without sheath flows.